Analysis of EUV spectra from N-shell tungsten ions observed with an electron beam ion trap
Tapasi Das, Yuri Podpaly, Joseph Reader, John D. Gillaspy, Yuri Ralchenko
Extreme ultraviolet spectra of highly charged tungsten ions were produced with an electron beam ion trap at the National Institute of Standards and Technology and recorded with a flat-field grazing-incidence spectrometer. The spectra were measured in the wavelength range 2.7 nm to 17.3 nm while the beam energy varied between 1.65 keV and 2.00 keV. At these energies, the ionization stages from Zr-like W34+ to Se-like W40+ ions were observed. Large-scale collisional-radiative modelling was used to identify the strong lines, including 15 new ones, which represent electric dipole n = 4-4 transitions in these ions. While a good quantitative agreement between theoretical and experimental data was found for almost all ions, some of the tentatively identified wavelengths in W35+ significantly disagree from all available calculations.